Cellulitis vs Erysipelas

Skin Structure and Function

• The skin is the largest organ of the body, maintaining homeostasis, protecting underlying tissue and organs, and shielding against mechanical injury, damaging substances, and UV rays.
• The skin consists of three layers: epidermis, dermis, and hypodermis.
• The epidermis provides a waterproof barrier and determines skin tone.
• The dermis contains tough connective tissue, hair follicles, and sweat glands.
• The hypodermis is composed of connective tissue, fat, and other tissues.

Staphylococci

• Mode of transmission: direct contact with infected individuals, contaminated healthcare workers, and fomites like bed linens.
• Clinical findings: folliculitis, a common skin condition characterized by inflamed hair follicles, typically caused by bacterial or fungal infections.
• Pseudofolliculitis barbae (razor bumps) is a condition where tightly curled hairs embed into the skin, causing raised, reddened papules or pustules.
• Treatment: allowing hair to grow out, using hair growth inhibitors.
• S. aureus is susceptible to oxacillin, a penicillin-derived antibiotic.
• Patient care: use standard precautions for minor skin, burn, and wound infections, and contact precautions for major infections.

Other Bacterial Skin Infections

• Staphylococcus epidermidis: a part of the skin's normal flora, frequently linked to "stitch abscess," UTI, and endocarditis, and causes infections in people with prosthetic equipment.
• Streptococcus pyogenes: a Gram-positive, aerotolerant bacterium that produces enzymes and toxins responsible for pathogenesis, transmitted through direct contact with infected individuals or fomites.
• Erysipelas (St. Anthony's fire): an acute infection characterized by a skin rash, may refer to ergotism, a result of long-term ergot poisoning.
• Cellulitis: a common bacterial skin infection causing redness, swelling, and pain, can spread and cause serious health problems if untreated, and is preventable through good wound care and hygiene.
• Necrotizing fasciitis: a rare, deadly infection of the skin and tissues, characterized by rapid spread, tissue death, and aggressive progression.

Clinical Features and Complications

• Erysipelas: abrupt onset with fever, bright red skin, and a well-defined border.
• Cellulitis: low-grade fever, spreading, hot, tender plaque, dull red skin, and a less well-defined border.
• Necrotizing fasciitis: complications include acute glomerulonephritis, nonsuppurative, immune-mediated complications, and skin infections.

Pseudomonas aeruginosa

• A heterotrophic, motile, Gram-negative, rod-shaped bacterium that grows via aerobic and anaerobic respiration.
• It is a facultative anaerobe that can cause infections, especially in people with compromised immune systems.